Permanent bonded magnets are well known. Bonded permanent magnets are typically fabricated by blending magnetic powders with a polymer as binder, and then molding the blend into desired shapes utilizing several commercial processing methods including injection molding, compression molding, extrusion, and calendering. Recently, bonded permanent magnets have experienced accelerated industrial applications due to their advantages, such as ability to be produced in intricate shapes, low weight and cost, superior mechanical properties and corrosion resistance. Nd2Fe14B is a particularly well known permanent magnet used in many industrial applications. Nd2Fe14B is known to adopt a tetragonal crystal structure (P42/mnm) with the easy magnetic axis along the c axis (Herbst, J. F., et al. Phys. Rev. B. 29, 4176-4178, 1984). Nd2Fe14B possesses a magnetic energy as large as 512 kJ/m3 (64 MGOe), with a Curie temperature Tc=585 K and a high magnetic anisotropy constant K1 of 4.5 MJ/m3 arising from the strong spin-orbit coupling in Nd (Sagawa, M., et al. J. Appl. Phys. 57, 4094, 1985. Magnet powder properties, processing temperature, loading factor, magnet density and degree of orientation are critical process variables for improving magnetic and mechanical properties of NdFeB bonded magnets.
However, current methods for producing them are being significantly challenged by an increasing demand for bonded permanent magnets of various intricate shapes and sizes, and with higher mechanical and magnetic field strengths. Although some additive manufacturing methods, such as binder jetting, have been attempted for producing bonded permanent magnets, the bonded magnet often exhibits sub-standard hard magnetic properties due to limitations in producing sufficiently dense parts. The bonded permanent magnets of the art also commonly exhibit a variability in magnetic strength throughout the part, which can be unacceptable in certain applications. Considering the above, there would be a significant advantage in a method that could produce permanent bonded magnets of any desired shape, intricacy, and size, and with higher than conventional mechanical strengths and magnetic field strengths, along with an improved uniformity of the magnetic field and physical properties throughout the bonded part.